Macular Edema in Diabetes Clinical Presentation

Updated: Aug 28, 2023
  • Author: Emmanouil Mavrikakis, MD, PhD; Chief Editor: Andrew A Dahl, MD, FACS  more...
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Specific inquiry should be made into risk factors for the development of diabetic retinopathy. These include the type of diabetes, the duration, and the degree of control. After 20 years of disease, nearly all patients with type 1 and 60% of patients with type 2 diabetes have some degree of retinopathy. The risk increases with the duration of disease. Hence, diabetic retinopathy is more likely to be present in patients older than 40 years.

The Diabetes Control and Complications Trial (DCCT) clearly demonstrated that tighter control of blood sugar is associated with reduced incidence of diabetic retinopathy. Glycosylated hemoglobin [HbA1c] should be less than 7%.

Proteinuria is a good marker for the development of diabetic retinopathy; thus, patients with diabetic nephropathy should be observed more closely. Elevated blood pressure increases the risk for retinopathy; patients with diabetes and hypertension may develop diabetic retinopathy with superimposed hypertensive retinopathy. Elevated triglyceride and lipid levels increase the risk for retinopathy, whereas normalization of lipid levels reduces retinal leakage and deposition of exudates.

Finally, diabetic retinopathy can progress rapidly in pregnant people, especially those with preexisting diabetic retinopathy.


Physical Examination

Funduscopy under stereopsis and high magnification should be performed on every patient with diabetes to assess for diabetic macular edema (DME) and diabetic retinopathy. An indirect ophthalmoscope does not provide adequate magnification for the diagnosis of diabetic macular edema.

Diabetic macular edema is defined as retinal thickening within two disc diameters of the center of the macula. Focal edema is associated with hard exudate rings resulting from leakage from microaneurysms. Diffuse edema results from breakdown of the blood-retinal barrier with leakage from microaneurysms, retinal capillaries, and arterioles.

Clinically significant macular edema (CSME), as defined by the Early Treatment Diabetic Retinopathy Study (ETDRS), exists with any of the following findings:

  • Retinal thickening within 500 µm of the center of the fovea

  • Hard, yellow exudates within 500 µm of the center of the fovea with adjacent retinal thickening

  • At least one disc area of retinal thickening, any part of which is within one disc diameter of the center of the fovea

Visual acuity should also be measured. Although visual acuity does not aid in the diagnosis of CSME—initially, at least, patients may have a visual acuity of 20/20—it is an important parameter in following the progression of CSME.

The status of the posterior hyaloid should also be determined. In CSME, the posterior hyaloid is detached, taut, and thickened.